Vasodilators are a fairly large group of drugs that have a vasodilating effect. Peripheral vasodilators dilate small veins and arteries by acting on the smooth muscle of blood vessels. Due to this, venous inflow to the muscle decreases, oxygen deficiency in the myocardium decreases. This group includes drugs that affect the distal parts of the vessels.
General information
Due to the intake of drugs of this group, blood vessels dilate, which reduces both the load on the heart muscle and its need for oxygen. This fact allows them to be used as antianginal agents. Peripheral vasodilators are drugs that act on resistive vessels and are indicated for the treatment of hypertension. This group of drugs began to be widely used in the last century, or rather, in the fifties. Initially, phentolamine was used to treat heart failure, but it was not widely used.applications due to the large number of adverse reactions.
The use of drugs included in this group should be carried out under the supervision of the attending doctor, as they can significantly reduce blood pressure, worsen the heart's blood supply.
Classification
Modern classification of peripheral vasodilators is based on drug action and site of application:
- Influence on blood vessels - mainly "Hydralazine" and "Fentolamine" affect arterial vessels, and "Prazosin" and nitrates affect venous vessels.
- Alpha-adrenergic receptor blockers – Phentolamine, Droperidol, Prazosin, Nifedipine, Hydralazine.
- Inhibitors of the converting enzyme - Enalapril, Captopril. The drugs promote the conversion of angiotensin 1 to angiotensin 2, and also act on the smooth muscles of small arteries.
- Direct effect on vascular smooth muscle - Prazosin, Sodium Nitroprusside, nitrates.
In addition, peripheral vasodilators are classified into:
- Venous - Molsidomin, Nitroglycerin.
- Arterial - "Hydralazine", "Fentolamine" "Minoxidil".
- Mixed - Prazosin, Nifedipine, Sodium Nitroprusside, Nitroglycerin and Molsidomin.
By the speed of the onset of the therapeutic effect:
- Immediate action - "Nitroglycerin", "Corvaton" by intravenous, sublingual or topical application.
- Delayed - Prazosin, Isosorbide dinitrate, Hydralazine.
Indications for use
Venous vasodilators are indicated for overload of the pulmonary circulation, they are:
- reduce pressure in the small circle;
- reduce left ventricular diastolic expansion;
- reduce the return of venous blood to the heart;
- reduce myocardial oxygen consumption.
Thus, peripheral vasodilators of this subgroup do not increase cardiac output, but only reduce pressure (pressure) in the pulmonary circulation. Drugs with a predominant action on small arteries reduce afterload, while they do not affect the pressure in the pulmonary circulation, i.e. the level of preload does not change. As a result, myocardial oxygen demand decreases and cardiac output increases. The main side effect of this group of drugs is the occurrence of hypotension and an increase in heart rate. Applicable under the following conditions:
- "Hydralazine" - with low cardiac output, with severe aortic or mitral regurgitation.
- "Fentolamine" - for catecholamine crisis in individuals with pheochromocytoma.
- Dihydropyridines - to treat hypertension.
Drugs with simultaneous effects on venules and arterioles affect pre- and afterload, so they are prescribed for the treatment of acute heart failure. And such a unique combination as Hydralazine + Isosorbide dinitrate, used in the treatment of chronic cardiacinsufficiency, within two years of admission contributes to a decrease in the risk of mortality.
Pharmacological action of vasodilators
The mechanism of action of peripheral vasodilators is different, this group includes drugs:
- blocking alpha-adrenergic receptors;
- Calcium ion antagonists;
- affecting smooth myofibrils of arterioles;
- converting enzyme inhibitors.
Despite the different mechanism of action, all drugs affect the post- and preload of the myocardium. Pharmacodynamic effects are manifested by a decrease in blood flow to the heart due to an increase in the capacity of the venous part of the vascular bed, and minute blood volume, due to an increase in the capacity of the arterial link of the autonomic vascular system.
The mechanism of action of drugs with the international non-proprietary name "Pentoxifylline"
The accumulation of cyclic adenosine monophosphate in the cellular tissue of vascular smooth muscles and in blood cells, as well as the inhibition of phosphodiesterase, underlies the mechanism of action of Pentoxifylline, a peripheral vasodilator, which is taken:
- Improves symptoms of cerebrovascular accident by reducing total peripheral resistance and slightly expanding coronary vessels. Shows a slight vasodilating effect.
- Inhibits the aggregation of red blood cells and platelets, stimulates fibrinolysis, reduces the concentration of fibrinogen in blood plasma, improving its viscosity.
Drug«Vazonite»
Is a medicine of long (prolonged) action. Pentoxifylline is the active substance, which contains 600 mg in one dosage form. Thanks to taking the drug "Vazonit 600":
- microcirculation improves in places of blood flow failure;
- blood fluidity improves due to the impact on deformed red blood cells;
- the elasticity of the erythrocyte membrane increases;
- increased blood viscosity decreases;
- platelet aggregation is blocked.
The drug is completely absorbed from the gastrointestinal tract. The extended form contributes to the uninterrupted flow of the active substance into the bloodstream. The maximum concentration in the blood is reached after three to four hours and persists for about twelve hours. More than ninety percent of the converted pentoxifylline is excreted by the kidneys.
Indications for the use of drugs with INN pentoxifylline
Doctors recommend Vasonit 600, as well as other drugs that have the active ingredient pentoxifylline, under the following conditions:
- Failure of blood flow of ischemic origin, acute and chronic.
- Discirculatory and atherosclerotic brain damage.
- Failure of peripheral circulation occurring against the background of inflammatory, as well as atherosclerotic and diabetic processes.
- As a symptomatic remedy for the treatment of the consequences that have arisen after cerebrovascular accidents.
- Failure of the functions of the middle ear of vascular origin, which is accompanied by hearing loss.
- Violation of blood circulation in the vessels of the eye.
- Trophic tissue disorders caused by failure of venous and arterial microcirculation.
Contraindications and side effects of drugs with the active substance pentoxifylline
According to the instructions for the use of "Pentilin" and other drugs with INN pentoxifylline, they are prohibited for admission when:
- Hypersensitivity to pentoxifylline.
- Pregnancy.
- Naturally fed.
- Retinal hemorrhage.
- Excessive bleeding.
- Acute myocardial infarction.
- Under the age of eighteen.
Adverse effects may occur from outside:
- hemostasis and cardiovascular systems;
- subcutaneous fat and skin;
- CNS;
- digestive system.
As well as allergic reactions and changes in some laboratory parameters.
Drug "Agapurin retard"
The active substance of this medicine is also pentoxifylline, which is 400 mg in one tablet. After administration, the active substance is gradually released from the dosage form and evenly enters the bloodstream. In addition to improving microcirculation, the drug has an angioprotective effect. Indications for prescribing a medication are violations:
- eye circulation;
- cerebral circulation (ischemic);
- functional sharpinner ear;
- venous and peripheral arterial blood flow provoked by diabetes mellitus, atherosclerosis;
- trophic as a result of varicose ulcerative lesions, frostbite, gangrene;
- peripheral arterial and venous circulation occurring against the background of such processes as infectious, diabetic, atherosclerotic.
And also in angioneuropathy and post-stroke conditions, both hemorrhagic and ischemic.
In individuals with diabetes mellitus, dosage adjustments of antidiabetic agents are often required. Otherwise, the risk of hypoglycemia is high. Take the drug twice a day at the same time, it is well tolerated. Adverse reactions are rare.
Medicinal product with INN Vincamine
"Vinoxin MB" has a selective vasoregulatory effect on cerebral circulation. Due to the intensive oxidation of glucose, it improves the metabolism of the brain. The supply of oxygen to neurons improves. Peripheral resistance of cerebral vessels stabilizes. In addition, the drug does not adversely affect the liver and kidneys. Doctors recommend "Vinoxin MB" to normalize cerebral circulation in case of violations:
- psychic;
- attention focus;
- memory;
- vision and hearing of vascular origin;
- craniocerebral posttraumatic;
- cerebral (after cerebral ischemia);
- and others.
The duration of the course of treatment is selected by the doctor individually. Its use is not recommended for pathologies that provoke an increase in intracranial pressure, acute stroke, heart rhythm disturbances, as well as for children, pregnant and lactating women. Side effects are minor. Do not increase the dose recommended by your doctor. With long-term use, liver monitoring is necessary.
Peripheral drugs
Currently, a large number of selective drugs have been developed that are successfully used for the treatment of heart failure, as well as hypertension. The following is a list of vasodilator drugs:
- Agapurin.
- "Bencilamane fumarate".
- Duzopharm.
- Complamin.
- Nicergoline.
- Pentamon.
- Pentoxifylline.
- Pentilin.
- Pentomer.
- Radomin.
- Ralofect.
- Sermion.
- Furazolidone and others
Each drug has a different pharmacological action. For successful treatment of pathology, it is important to choose the right remedy. To avoid unpleasant consequences, before using the medicine, you should read the instructions for use and follow all the recommendations of your doctor.
